"Visual check," said the co-pilot drily, to Joe. "We had a signal to give. Individual to this plane. We didn't tell it to you. You couldn't duplicate it." Joe worked it out painfully. The visual effect of one propeller seen through another--that was identification. It was not a type of signaling an unauthorized or uninformed passenger would expect. "Also," said the co-pilot, "we have a television camera in the instrument board yonder. We've turned it on now. The interior of the cabin is being watched from the ground. No more tricks like the phony colonel and the atom bomb that didn't 'explode.'" Joe sat quite still. He noticed that the plane was slanting gradually downward. His eyes went to the dial that showed descent at somewhere between two and three hundred feet a minute. That was for his benefit. The cabin was pressurized, though it did not attempt to simulate sea-level pressure. It was a good deal better than the outside air, however, and yet too quick a descent meant discomfort. Two to three hundred feet per minute is about right. The ground took on features. Small gulleys. Patches of coloration too small to be seen from farther up. The feeling of speed increased. After long minutes the plane was only a few thousand feet up. The pilot took over manual control from the automatic pilot. He seemed to wait. There was a plaintive, mechanical _beep-beep_ and he changed course. "You'll see the Shed in a minute or two," said the co-pilot. He added vexedly, as if the thing had been bothering him, "I wish I hadn't missed that sandy-haired guy putting his hand in the wheel well! Nothing happened, but I shouldn't have missed it!" Joe watched. Very, very far away there were mountains, but he suddenly realized the remarkable flatness of the ground over which they were flying. From the edge of the world, behind, to the very edge of these far-distant hills, the ground was flat. There were gullies and depressions here and there, but no hills. It was flat, flat, flat.... The plane flew on. There was a tiny glimmer of sunlight. Joe strained his eyes. The sunlight glinted from the tiniest possible round pip on the brown earth. It grew as the plane flew on. It was half a cherry stone. It was half an orange, with gores. It was the top section of a sphere that was simply too huge to have been made by men. There was a thin thread of white that ran across the dun-colored range and reached that half-ball and then ended. It was a highway. Joe realized that the half-globe was the Shed, the monstrous building made for the construction of the Space Platform. It was gigantic. It was colossal. It was the most stupendous thing that men had ever created.